A UBEC provides a nice efficient way to power your Pi from batteries

We recently started selling a USB powerbank which can be used to power the Raspberry Pi robot kit that we sell. Using the powerbank provides great battery life, but we’re still interested in making the robot run well from AA batteries, as this may be the cheaper option if you already have rechargeable batteries and a charger lying around.

Testing battery life

Therefore, we’re modifying the kit a bit to include a UBEC (Universal Battery Elimination Circuit). This is an efficient switching voltage regulator which takes the load off the linear voltage regulator of the Mini Driver and improves the running time of a robot being powered by AA batteries a lot. This post gives some details about why we’re making this change and also describes a battery testing script that we’ve written to determine what kind of run times can be expected for different methods of powering the Raspberry Pi robot.

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The new Model B+

So, the big news this week (if you’re a Raspberry Pi fan) is that the Raspberry Pi foundation announced the release of an upgraded version of the Model B Pi, the Model B+. The Raspberry Pi Model B+ is a really nice incremental update of the Model B, and it’s especially good for people wanting to use the Pi in robotic projects. This is because, alongside extra USB ports, it now uses switching voltage regulators which means that it consumes less power (between 0.5W to 1W less) and therefore it will last longer on batteries.

As soon as we got a Model B+ this week, we put it onto one of our Raspberry Pi Camera Robots, and it works great. The Model B+ has a different layout and mounting holes than the Model B so we’ve updated the assembly instructions for the robot to show how the Model B+ should be mounted.

We’ve also released a new version of the software for the robot, as the Model B+ needs different drivers for its USB and network ports. This new software has a few bugfixes, and also allows the robot to be driven at slower speeds than before. This new feature may not sound like much, but with the old software, the motors often couldn’t be made to go slower than about 33% speed before they stalled due to friction in the gearboxes. Now by driving the motors in a different way, we get the motors to turn with more torque at lower speeds to overcome this friction. This means that it’s easier to drive the robot whilst looking through the camera, and makes making precise turns easier.

The new SD card image can be downloaded here. Other options for getting the software are discussed here.

We had a great response to a recent blog post we wrote, describing how to build a Raspberry Pi robot that you can drive around using a tablet, smartphone or PC. Therefore we’ve carried on developing the software for it, and are pleased to announce the update today. The changes that we’ve made to the software have largely been to support cool things that we want to do with the robot in the future, but features that users of the robot will notice are

• much faster camera streaming. Initially the camera was streaming images at about 4-5 frames per second using raspistill and mjpg-streamer, but we’ve now written our own camera streamer, and got it streaming at 15fps which is much smoother, and makes driving the robot around a lot easier.
• support for more WiFi dongles when working as an access point. Our previous software release mainly worked with WiFi dongles that used the same chipset as the Edimax EW-7811Un (the hostapd rtl871xdrv driver). It was possible to get it to work with other WiFi dongles that used the hostapd nl80211 driver, but it required a fairly technical user. Now our software should work with a much wider range of WiFi dongles with no change required.
• we’ve added a shutdown button. Previously the robot was turned off by just cutting off the power. This was very unlikely to corrupt the SD card as nothing was written to it, but a lot of users felt uncomfortable with not doing a proper shutdown. Now a shutdown button in the web interface provides peace of mind.
• more configuration options. The configuration webpage of the robot has been expanded to offer more options to control the movement of the robot.

As before, there are multiple options for getting hold of this software. If you already have an SD card then you can download an SD card image with all of the software installed here (go for the most recent version). Update: If you use our SD card image, please remember to expand it after installation by running

sudo raspi-config

and choose the ‘Expand Filesystem’ option.

Alternatively, we sell SD cards with the image preloaded in our store. Finally, for those who want to set up the software from scratch, or who want to modify it for their own robotic projects, we give full details for building the SD card, and installing all the software, here.

We believe that the Raspberry Pi is a great platform for robotics, and have got a number of tutorials for our Raspberry Pi Camera bot lined up for the coming months. If there’s anything in particular you’d like to see, please let us know.

Last Saturday we attended the Linux User Pi Jam, in Poole, and had an absolute blast. The Jam was held at the RNLI college, which is a great location for an event, and we met some very interesting people at the Jam.

We’re glad to see that robotics is rising in popularity as something to do with your Pi. We ran a store at the Jam, and other robotics vendors there included The Little British Robot Company and PiBorg (with their very cool DoodleBorg tank). Ben from Phenoptix was also there with a neat little laser cut robot arm. We saw some cool Raspberry Pi robot projects from Leo White, and had a nice chat with Ian Renton, the guy behind the Raspberry Pi tank.

In the afternoon we gave a talk on combining the power of Arduino with the Pi to build Raspberry Pi robots as we have with our Camera Bot. For anybody interested the slides can be found here.

Pi Jams are a great way to meet interesting people, and get ideas for your next Pi project, if you haven’t been to one yet then we recommend that you keep an eye out for one in your area and head along.

A couple of months ago, Dawn Robotics went to the fantastic Cambridge Pi Jam organised by Michael Horne and Tim Richardson. Whilst there, I gave a talk on building a mobile robot with the Raspberry Pi (such as the camera robot we talk about in this blog post). The talk was aimed at quite a high level, and looked at 7 key areas you should think about when building a mobile robot.

Well, I recently found out that there was a video of the talk online (along with videos of all the other talks at the Jam). Therefore I thought that I’d link to it here, along with the slides for the talk. The sound quality is not too great, and I need to work on my presenting style, but hopefully it’ll be useful to people thinking of building their own robot. If you’ve got any questions, or would like more information on any of the areas talked about in the video, please post on our forums.

Also, for those that are in the area, we’ll also be giving a talk at the Linux User Raspberry Pi Jam being held in Poole this Saturday (5th April 2014). A small number of tickets for the Jam are still available here. This talk will mainly be about using the Pi with an Arduino, but we’ll still try to squeeze in some robots.